| 摘要 |
PURPOSE:To obtain a stable digital communication and to evade the degrading in the reliability and service life of a laser diode by using a laser diode whose optical output-current characteristic has a super linear characteristic area for a light emitting element. CONSTITUTION:As the light emitting element, a gain guide type semiconductor laser diode is constituted by using the laser diode whose optical output-current L-I characteristic curve shown by the full line curve 1 of the figure has the super linear characteristic area. This means that a current limited area is provided for that a current collectively flows within the oscillation area of an active layer. In this case, as the degree of light excitation increases, a dip in gain occurs in a gain distribution curve 3A. As a result, a virtually positive refraction factor distribution is generated in the middle of a refraction distribution curve 3B, accordingly, the light shifts to a wave-guided state from a non- wave-guided state, and thus the super linear characteristic area in which the optical output is increased in proportion to the aggregation of input current. Since the modulation is executed by using this area, the degrading of differential efficiency can be improved, therefore, the temperature rise is suppressed, as a result, the life and the reliability of the titled equipment can be improved. |
